The invention is based on an idling/final speed governor for internal combustion engines. The exacting requirements imposed on the exhaust-gas quality and on the specific performance with regard to the fuel consumption of the allocated internal combustion engine impose corresponding requirements on an idling/final speed governor leading to increasingly more complicated governor designs. On the one hand, this has increased the manufacturing costs of the governors, and on the other hand, special embodiments of the governors have arisen which can be used only for certain internal combustion engines to meet certain demands.
In a known idling/final speed governor (Swiss Patent Specification No. 319,357), the full-load stop of the quantity-control member (control rod) is arranged on a swing-out lever which, via a crescent-shaped lever articulating this swing-out lever, is always swung out of the stop position when the centrifugal-weight regulator moves into its inoperative or initial position. At the same time, a weak pressure spring is compressed. In this stop-free adjustment, the control rod can be displaced into a starting position, i.e. into a position beyond the full-load position, in which an extra fuel quantity required for starting the cold internal combustion engine is delivered by the injection pump. When the internal combustion engine is started at an adequate speed, and the centrifugal-weight regulator, driven by the centrifugal weights, lifts from the crescent-shaped lever, the pressure spring shifts this crescent-shaped lever to the extent that the level bearing the stop is swung back into the full-load stop position so that only the full-load quantity can be delivered as a maximum injection quantity.
Quite apart from the fact that this design is relatively complicated and relatively laborious to assemble, setting the locking and release of the starting travel requires additional assembly time. Moreover, the pressure spring acting on the crescent-shaped lever not only acts in the inoperative position of the centrifugal-weight regulator but also in the idling speed range on its regulating sleeve, so that the force of the pressure spring is superimposed on the force of the idling spring acting against the centrifugal forces of the centrifugal weights. This neutralizing of the pressure spring disadvantageously produces a corresponding "jump" in the idling control curve, which for the operation of the internal combustion engine is manifested as so-called "surging" during idling.
The harmful substances in the exhaust gas always increase if the extra starting quantity required for starting the internal combustion engine is not cut back again by the governor after starting or if, for example when the accelerator pedal is fully depressed, the full-load stop limiting the full-load quantity does not come into action and the extra starting quantity is thereby injected. The latter, in this known governor, can disadvantageously occur if the internal combustion engine, when travelling downhill, is disengaged for saving fuel and is stopped by interruption in the injection. During this procedure, the crescent-shaped and the swing-out levers are displaced by the centrifugal-weight regulator into a position in which the full-load stop is no longer effective. If, for example on an uphill roadway, the internal combustion engine is started up again after engaging while utilising the moving vehicle mass, which can also be effected by the starter, and as long as the accelerator pedal is fully depressed, the control rod maintains the position previously assumed for the extra starting quantity. The swing-out lever, with its stop, is certainly pushed again in the direction of the locking position by the pressure spring, but without being able to exert an effect on the control rod, because the latter is already in the position for the extra starting quantity. The internal combustion engine therefore receives an insufficiently combustible extra quantity of fuel, in fact until the accelerator pedal is throttled back and the control rod is pulled into a normal working position which is then limited in the direction of maximum injection quantity by the full-load stop.
It is known that the fuel quantity combustible free of smoke is greater if the combustion air supplied to the internal combustion engine is supercharged (compressed). Accordingly, the full-load stop is adjustable between aspirated operation and supercharged operation, which is mostly effected by a device on the fuel injection pump side remote from the governor (Bosch--publication VDT-AKP 4/1, 1st issue August 73; p. 34). The end stop of the control rod is also arranged here on this side of the injection pump, which end stop also determines the maximum extra starting quantity. This end stop must be positioned in such a way that, in supercharged operation, the requisite full-load injection quantity can still be delivered, which in some internal combustion engines can be greater than the extra starting quantity in aspirated operation. As a result of the design, however, the end stop for the extra starting quantity permits a further, even if small, stroke in the direction of greater injection quantity than is necessary for the full-load quantity during super-charged operation. This position, due to the design, of the end stop of the control rod causes a relatively high proportion of toxicants to develop in the exhaust gas, for in most internal combustion engines an extra starting quantity which is the same as or greater than the full-load quantity required for super-charged operation leads to exhaust gas emissions which are harmful to the environment.
The applicants have also disclosed idling/final speed governors of the type described in which the position of the lever which bears the stop of the control rod and can be pivoted by the crescent-shaped lever adjusted in such a way by a device inside the space of the speed governor, which device works as a function of the positional [sic] pressure, that in one position there is a full-load stop for aspirated operation and in the other position there is a full-load stop for supercharged operation. But even in this way the abovementioned disadvantages are not avoided.
It is also known (German Offenlegungsschrift No. 3,246,869) to disengage such a full-load stop, variable as a function of its supercharge pressure, via an operating magnet in order to thereby make possible an extra starting quantity. In this govenor, there is also the fact that an electrical control means is required for starting, and if this means fails, an extra starting quantity and thus starting of the internal combustion engine is not possible or is made very difficult.
In a known idling/final speed governor of the generic type (German Offenlegungsschrift No. 3,414,846), the extra starting quantity is controlled via a starting spring which is compressed for starting, after appropriately fully depressing the accelerator pedal and displacing the control rod into the position for extra starting quantity, and is then extended again, after starting, in order to displace the control rod into a normal working position between idling and full load. During this procedure, the starting spring acts on a full-load stop bolt which, having a head, with the spring extended and in the initial position of the bolt, limits the full-load injection quantity. However, for this speed governor, which is simpler per se, the position of the stop cannot be changed as a function of operating parameters, such as, for example, the supercharge pressure, without at the same time engaging in the control range of the starting spring.